The present invention relates to an apparatus and method for sensing a condition of a vehicle. More Particularly the present invention relates to an apparatus and method for sensing a parameter indicative of a vehicle rollover condition.
In order to detect a vehicle rollover, the vehicle may be equipped with a sensor for detecting the occurrence of a vehicle rollover condition. The sensor typically is connected to a controller that controls actuation of one or more actuatable devices, such as an occupant restraint and/or an active suspension system, in response to a sensed rollover condition.
For example, U.S. Pat. No. 5,825,284 discloses a vehicle system having a sensor that provides a signal indicative of lateral acceleration of the vehicle. A processor calculates a roll moment based on the sensor signal, which is visually displayed as an indication of the likelihood of a vehicle rollover condition.
Various devices also have been proposed for detecting an angular orientation of an object. For example, U.S. Pat. No. 5,329,121 to Leviton, U.S. Pat. No. 4,207,463 to Iyeta, U.S. Pat. No. 5,670,780 to Lewis, U.S. Pat. No. 5,103,090 to Weiner et al., and U.S. Pat. No. 4,320,293 to Guretzky each discloses a rotation angle measuring device that senses rotation of a body using optical emitters and detectors.
A first exemplary embodiment of the present invention provides a vehicle rollover sensor that includes a rotor having a rotor axis and which is mountable within the vehicle. The rotor is inertially balanced and freely rotatable about the rotor axis. The sensor also includes a detector for detecting rotation of the rotor relative to the rotor axis. The detector is operative to provide a detector signal indicative of the detected rotation. The detector signal is used to determine the occurrence of a vehicle rollover condition.
Another exemplary embodiment of the present invention provides a vehicle rollover sensor that includes a detector for detecting a parameter indicative of vehicle rollover condition and for providing a first signal indicative thereof. The vehicle rollover sensor also includes means for removing a time-averaged portion of the detected parameter from the first signal and for providing a second signal indicative of the remaining portion of the detected parameter. The second signal has a characteristic indicative of a vehicle rollover condition.